Many useful systems contain and/or operate using a fluid (gas, liquid or combination of both). For example, automobiles have several systems which contain and utilize a fluid in their operation, including the fuel system, the exhaust system, the heating, cooling and ventilation (HVAC) system, and the hydraulic power steering and brake systems, to name but a few. There are also many industrial machines, household HVAC systems and other devices that utilize a fluid to operate, which fluid may be for example a gas such as air or evaporated system liquid, fuel, hydraulic fluids, manufactured gases and liquids, etc. In all of these systems and circumstances, the fluid system must be properly sealed to prevent leakage of the system fluid; however, leaks in such fluid systems can be very difficult to detect and/or locate, either because the leak is small or in a location that is not easily accessible.
Vapor generating apparatuses or devices are known for generating a visible gas or vapor that is mixed with air supplied thereto under pressure so that the mixture can be delivered to a fluid system undergoing testing for leaks. Although these apparatuses are commonly described as smoke machines, the “smoke” is typically a non-toxic aerosol mist produced by evaporation and condensation at controlled temperatures rather than actual smoke. In the context of the following description, “smoke” refers to either a solution (e.g., petroleum-based) that is heated and vaporized or to a visible aerosol mist, spray, gas, vapor or combination thereof. By observing any visible “smoke” which exits a small and often visually imperceptible hole in the system under test, an indication is provided to the observer of the presence and location of the leak so that a repair might be made.
The use of smoke machines to detect leaks in internal combustion engine systems are well known in the art. More specifically, such leak detection systems are extensively used in engine diagnostic and maintenance procedures, and in particular can be used to find leaks in EVAP systems, valves, gaskets, hoses, vacuum lines and reservoirs, throttle bodies, EGR valves, air intake ducting, intake manifolds, and exhaust systems among others.
Historically, smoke machines have been designed to deliver vapor into the automobile system under test at the standard EVAP test pressure of 12-14 inches of water column pressure (0.47 psi). Leak testing of the different automobile systems of naturally aspirated internal combustion engines at this low pressure has been quite effective and useful. Since the maximum load on the air intake system of a naturally aspirated internal combustion engine is approximately 1 psi of vacuum at idle, a test pressure (0.47 psi) at approximately half of maximum load (1 psi) is adequate to find leaks.
However, in an effort to gain more power using less fuel, automobile manufacturers are increasingly turning to a gas compressor used for forced induction or boosting the air induction system of internal combustion engines by utilizing mechanical superchargers, exhaust gas turbines, turbo chargers and multiple turbo chargers among others. The amount of boost or increased intake pressure in these boosted engines can be 6-9 psi on the low end of smaller engines, up to and exceeding 36-40 psi under full load for larger engines. Consequently, the standard EVAP test pressure of 0.471 psi is insufficient to detect and locate leaks when the system under test is under 12 to 80 times more pressure under full load.
Vapor generating devices specifically designed or adapted to detect leaks in such high pressure forced induction systems are also known in the art. In the example of U.S. Pat. No. 8,737,826 entitled HIGH PRESSURE SMOKE MACHINE and dated May 27, 2014, there is described a smoke machine that can produce a controlled vapor at a test pressure of up to and exceeding 30 psi, for safe usage for leak determination and location in internal combustion engines with forced induction systems.
Different types of fluid systems clearly have different inspection pressure requirements. As such, a vapor generating device designed to operate at a specific test pressure is only useful for leak detection and location in those fluid systems for which the respective inspection pressure requirement matches or is within a tolerance of the specific test pressure. For example, a smoke machine designed to produce vapor at the standard test pressure of 0.471 psi can be used for leak detection and location in a naturally aspirated internal combustion engine, but likely would not be efficient in a boosted, forced induction engine. Similarly, a smoke machine designed to produce vapor at a test pressure of 30 psi can be used for leak detection and location in a forced induction engine, but not in a naturally aspirated internal combustion engine, since the excessive test pressure would damage the engine systems that are designed to contain a much lower pressure (e.g. 1 psi).
In the auto mechanic industry, or other such similar industrial/commercial vehicle service industry, it becomes expensive to stock multiple different smoke machines in order to be able to perform leak detection and location on different fluid systems having different inspection (test) pressure requirements. Even if a smoke machine could be adapted (e.g. by changing a heating surface area) to produce vapor at different test pressures, it would be inefficient and time consuming to have to perform such adaptation each time a fluid system to be verified requires a different inspection pressure.
Furthermore, equipment having replaceable parts require maintenance to replace such parts. It is desirable to make the replacement of such part as easy and rapid as possible and to require as little expertise as possible so as to make replacing parts cheap and to make the equipment serviceable by non-professionals.
Moreover, in smoke machines, the efficient generation of smoke from fuels for such smoke, by wasting as little energy as possible, e.g. on heat that is not put to use towards the creation of smoke, is essential.
Consequently, there exists a need in the industry for an improved vapor generating device that can be easily serviced while efficiently utilising fuel and energy towards smoke creation and that can be easily manipulated to test different fluid systems having different inspection pressure requirements.